Solution for Program #RMJPQ3 given on http://ronitmukherjee.com/practice-javascript-programs-for-interview/#RMJPQ4

RMJPQ4.js

//https://jsfiddle.net/mukherjeeronit/906gx2cb/

function findTopper(students = []) {
 var topper = {
  percentage: 0
 };

 for (var i = 0; i < students.length; i++) {
  var student = students[i];


  var marks = Object.values(student.marks); //[66,80,97]
  var totalMarks = marks.reduce(function(total, mark) {
   return total + mark;
  }, 0);
  var percentage = (totalMarks / (marks.length * 100)) * 100;

  if (percentage > topper.percentage) {
   topper = student;
   topper.percentage = percentage;
  }
 }

 return topper;
}

var students = [{
  name: "Sumit",
  marks: {
   english: 60,
   maths: 80,
   science: 97
  }
 },
 {
  name: "Amit",
  marks: {
   english: 65,
   maths: 90,
   science: 77
  }
 }
];

var topper = findTopper(students);

console.log(topper.name + " has topped the class with " + topper.percentage + "%");